U.S. patent number 6,989,408 [Application Number 10/450,338] was granted by the patent office on 2006-01-24 for method for preparing acryl based impact-reinforcement.
This patent grant is currently assigned to LG Chem, Ltd.. Invention is credited to Chang-Sun Han, Yong-Hun Lee, Dong-Jo Ryu.
United States Patent |
6,989,408 |
Ryu , et al. |
January 24, 2006 |
Method for preparing acryl based impact-reinforcement
Abstract
The present invention relates to a preparation method of an
acryl-based impact-reinforcement, and more particularly, to a
preparation method of an acryl-based reinforcement prepared by
blending latex having large particles and latex having small
particles, being capable of enhancing impact-resistance of a
polyvinyl chloride (PVC) resin. The present invention provides a
method of preparing an acryl-based impact reinforcement comprising
a step of blending a) 50 to 90 parts by weight of latex having
large particles with a particle size of 200 to 500 nm and a
core-shell structure and b) 10 to 50 parts by weight of latex
having small particles with a particle size of 60 to 140 nm and a
core-shell structure. In addition, the present invention provides
an impact-reinforcement prepared by the method of the present
invention, and a polyvinyl chloride (PVC) composition comprising
the same.
Inventors: |
Ryu; Dong-Jo (Yeosoo,
KR), Han; Chang-Sun (Yeosoo, KR), Lee;
Yong-Hun (Yeosoo, KR) |
Assignee: |
LG Chem, Ltd.
(KR)
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Family
ID: |
19703021 |
Appl.
No.: |
10/450,338 |
Filed: |
December 13, 2001 |
PCT
Filed: |
December 13, 2001 |
PCT No.: |
PCT/KR01/02162 |
371(c)(1),(2),(4) Date: |
June 11, 2003 |
PCT
Pub. No.: |
WO02/48223 |
PCT
Pub. Date: |
June 20, 2002 |
Prior Publication Data
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|
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Document
Identifier |
Publication Date |
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US 20050101732 A1 |
May 12, 2005 |
|
Foreign Application Priority Data
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|
|
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Dec 13, 2000 [KR] |
|
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2000-76010 |
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Current U.S.
Class: |
523/201;
525/71 |
Current CPC
Class: |
C08F
265/06 (20130101); C08F 285/00 (20130101); C08L
27/06 (20130101); C08L 51/003 (20130101); C08F
265/06 (20130101); C08F 2/22 (20130101); C08F
285/00 (20130101); C08F 220/12 (20130101); C08L
27/06 (20130101); C08L 51/003 (20130101); C08L
2666/24 (20130101); C08L 2666/24 (20130101) |
Current International
Class: |
C08F
285/00 (20060101) |
Field of
Search: |
;523/201 ;525/71 |
References Cited
[Referenced By]
U.S. Patent Documents
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|
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4535124 |
August 1985 |
Binsack et al. |
4581408 |
April 1986 |
Trabert et al. |
5612413 |
March 1997 |
Rozkuszka et al. |
5798414 |
August 1998 |
Mishima et al. |
5969042 |
October 1999 |
Tiefensee et al. |
|
Foreign Patent Documents
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0 522 605 |
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Jan 1993 |
|
EP |
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05-302009 |
|
Nov 1993 |
|
JP |
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10-324787 |
|
Dec 1998 |
|
JP |
|
11-147991 |
|
Jun 1999 |
|
JP |
|
2000-319482 |
|
Nov 2000 |
|
JP |
|
Other References
International Search Report; PCT/KR01/02162; Mar. 12, 2002. cited
by other .
International Preliminary Examination Report; PCT/KR01/02162; Mar.
18, 2003. cited by other.
|
Primary Examiner: Mullis; Jeffrey
Attorney, Agent or Firm: Cantor Colburn LLP
Claims
What is claimed is:
1. A method of preparing an acryl-based impact reinforcement
comprising the step of blending: a) 50 to 90 parts by weight of
latex having large particles with a mean particle size of 200 to
500 nm and a core-shell structure; and b) 10 to 50 parts by weight
of latex having small particles with a mean particle size of 60 to
140 nm and a core-shell structure; wherein the core-shell structure
of the large particles is formed by a polymerization method
comprising: i) polymerization of a first emulsified mixture
comprising 97.0 to 99.9 parts by weight of alkyl acrylate having an
alkyl group of C.sub.2 to C.sub.8; 0.1 to 3.0 parts by weight of
cross-linking agent; 0.01 to 3.0 parts by weight of a
polymerization initiator; 0.1 to 10.0 parts by weight of an
emulsifier; and 1000.0 parts by weight of ion-exchange water at 60
to 80.degree. C. to prepare a first seed comprising a first latex;
ii) polymerization of a second emulsified mixture comprising 97.0
to 99.9 parts by weight of alkyl acrylate having an alkyl group of
C.sub.2 to C.sub.8; 0.1 to 3.0 parts by weight of cross-linking
agent; 0.1 to 4.0 parts by weight of an emulsifier; and 80 parts by
weight of ion-exchange water, by adding 0.01 to 3.0 parts by weight
of a polymerization initiator to the first seed while adding the
second emulsified mixture continuously to the seed, to form a
second latex; iii) polymerization of a third emulsified mixture
comprising 97.0 to 99.9 parts by weight of alkyl acrylate having an
alkyl group of C.sub.2 to C.sub.8; 0.1 to 3.0 parts by weight of
cross-linking agent; 0.1 to 4.0 parts by weight of an emulsifier;
and 80 parts by weight of ion-exchange water, by adding 0.01 to 3.0
parts by weight of a polymerization initiator to the second latex
while adding the third emulsified mixture continuously to the
second latex, to form a third latex; and iv) polymerization of a
fourth emulsified mixture comprising 80 to 100 parts by weight of
alkyl methacrylate having an alkyl group of C.sub.1 to C.sub.4; 10
parts by weight or less of alkyl acrylate selected from the group
consisting of ethyl acrylate, methyl acrylate, and butyl acrylate;
10 parts by weight or less of nitrile selected from the group
consisting of acrylonitrile, and methacrylonitrile; 0.1 to 4.0
parts by weight of emulsifier; and 150 parts by weight of
ion-exchange water, by adding 0.01 to 3.0 parts by weight of a
polymerization initiator to the third latex while adding the fourth
emulsified mixture continuously to the third latex.
2. The method of preparing an acryl-based impact reinforcement
according to claim 1 wherein the swelling index of a) latex having
large particles and b) latex having small particles respectively
ranges from 2.0 to 12.0.
3. The method of preparing an acryl-based impact reinforcement
according to claim 1 wherein the rubber content of the cores of a)
latex having large particles and b) latex having small particles
respectively ranges from 70 to 95 wt % based on a total content of
the acryl-based impact reinforcement.
4. The method of preparing an acryl-based impact reinforcement
according to claim 1 wherein the cores of latex having large and
small particles respectively comprises i) 97.0 to 99.9 parts by
weight of alkyl acrylate having an alkyl group of C.sub.2 to
C.sub.8; and ii) 0.1 to 3.0 parts by weight of cross-linking
agent.
5. The method of preparing an acryl-based impact reinforcement
according to claim 4 wherein the alkyl acrylate is one or more
monomers selected from the group consisting of methyl acrylate,
ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl
acrylate, hexyl acrylate, octyl acrylate, and 2-ethylhexyl
acrylate, and a homopolymer thereof or a copolymer thereof.
6. The method of preparing an acryl-based impact reinforcement
according to claim 4 wherein the cross-linking agent is one or more
monomers selected from the group consisting of 1,3-butandiol
diacrylate, 1,3-butandiol dimethacrylate, 1,4-butandiol diacrylate,
1,4-butandiol dimethacrylate, allyl acrylate, allyl methacrylate,
trimethylol propane triacrylate, tetraethylene glycol diacrylate,
tetraethylene glycol dimethacrylate, and divinylbenzene, and a
homopolymer thereof or a copolymer thereof.
7. The method of preparing an acryl-based impact reinforcement
according to claim 1 wherein each shell of latex having large
particles and latex having small particles comprises: i) 80 to 100
parts by weight of alkyl methacrylate having an alkyl group of
C.sub.1 to C.sub.4; ii) 10 parts by weight or less of alkyl
acrylate selected from the group consisting of ethyl acrylate,
methyl acrylate, and butyl acrylate; and iii) 10 parts by weight or
less of nitrile selected from the group consisting of acrylonitrile
and methacrylonitrile.
8. The method of preparing an acryl-based impact reinforcement
according to claim 1 wherein the blending step is performed by
adding latex having large particles to latex having small
particles, coagulating a resulting mixture with an electrolyte, and
filtering the coagulated slurry to obtain an impact
reinforcement.
9. The method of preparing an acryl-based impact reinforcement
according to claim 8 wherein the electrolyte is calcium
chloride.
10. The method of preparing an acryl-based impact reinforcement
according to claim 1 wherein the emulsifier is selected from the
group consisting of unsaturated fatty acid potassium salt, oleic
acid potassium salt, an ionic emulsifier, and a nonionic
emulsifier.
11. The method of preparing an acryl-based impact reinforcement
according to claim 1 wherein the polymerization initiator is
selected from the group consisting of ammonium persulfate,
potassium persulfate, benzoyl peroxide, azobis butyronitrile, butyl
hydroperoxide, and cumene hydroperoxide.
12. The method of preparing an acryl-based impact reinforcement
according to claim 1 wherein b) the latex having small particles is
prepared by a polymerization method comprising: i) polymerization
of a first emulsified mixture comprising 97.0 to 99.9 parts by
weight of alkyl acrylate having an alkyl group of C.sub.2 to
C.sub.8; 0.1 to 3.0 parts by weight of cross-linking agent; 0.01 to
3.0 parts by weight of a polymerization initiator; 20 to 80 parts
by weight of an emulsifier; and 1000 parts by weight of
ion-exchange water at 60 to 80.degree. C. to prepare a first seed
comprising a first latex; ii) polymerization of a second emulsified
mixture comprising 97.0 to 99.9 parts by weight of alkyl acrylate
having an alkyl group of C.sub.2 to C.sub.8; 0.1 to 3.0 parts by
weight of cross-linking agent; 0.1 to 4.0 parts by weight of an
emulsifier; and 80 parts by weight of ion-exchange water, by adding
0.01 to 3.0 parts by weight of a initiator to the seed while adding
the emulsified mixture continuously to the first seed, to form a
second latex; iii) polymerization of a third emulsified mixture
comprising 97.0 to 99.9 parts by weight of alkyl acrylate having an
alkyl group of C.sub.2 to C.sub.8; 0.1 to 3.0 parts by weight of
cross-linking agent; 0.1 to 4.0 parts by weight of an emulsifier;
and 80 parts by weight of ion-exchange water, by adding 0.01 to 3.0
parts by weight of a initiator to the second latex while adding the
emulsified mixture continuously to the second latex, to form a
third latex; and iv) polymerization of a fourth emulsified mixture
comprising 80 to 100 parts by weight of alkyl methacrylate having
an alkyl group of C.sub.1 to C.sub.4; 10 parts by weight or less of
alkyl acrylate selected from the group consisting of ethyl
acrylate, methyl acrylate, and butyl acrylate; 10 parts by weight
or less of nitrile selected from the group consisting of
acrylonitrile, and methacrylonitrile; 0.1 to 4.0 parts by weight of
an emulsifier; and 150 parts by weight of ion-exchange water, by
adding 0.01 to 3.0 parts by weight of a initiator to the third
latex while adding the emulsified mixture continuously to the third
latex.
Description
CROSS REFERENCE TO RELATED APPLICATION
This application is based on application No. 2000-76010 filed in
the Korean Industrial Property Office on Dec. 13, 2000, the content
of which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a preparation method of an
acryl-based impact-reinforcement, and more particularly, to a
preparation method of an acryl-based impact-reinforcement, in which
latex having large particles and latex having small particles are
blended together to enable the enhancement of an impact-resistance
of a polyvinylchloride (PVC) resin.
(b) Description of the Related Art
An impact-reinforcement is used for enhancing the impact-resistance
of the polyvinyl chloride resins, and the different types of
impact-reinforcement include a methyl
methacrylate-butadiene-styrene-based (MBS) resin, a chlorinated
polyethylene-based (CPE) resin, and an acryl-based resin. Among
these resins, the acryl-based resin is widely used for products
exposed to the sun, since it has a high weather-resistance. For
example, PVC window sash needs both high impact-resistance and
weather-resistance, and impact reinforcement which is prepared by
grafting a rubbery elastomer core comprising alkyl acrylate polymer
with a glassy methacryl-based polymer shell that is highly
compatible to the PVC resin showed both necessary properties.
The manner in which the core is bonded with the shell chemically is
a critical factor in realizing beneficial properties of acryl-based
impact reinforcements with the core-shell structure. In addition,
the degree of cross-linking of dispersed rubber particles in
matrix, the content of rubber particles, the size of rubber
particles, and the swelling index of rubber particles to solvent
are critical factors that affect the impact resistance of
acryl-based impact reinforcements.
In order to enhance the impact resistance of polyvinyl chloride
resin, an acryl-based impact reinforcement has been prepared by
emulsion polymerization which includes both core and shell
polymerization.
In the core polymerization, alkyl acrylate monomers having one
double bond and low glass transition temperature are polymerized,
and the alkyl acrylate polymer gives an acryl-based impact
reinforcement with both weather-resistance due to the absence
double bond after polymerization and impact-resistance due to the
low glass transition temperature. Cross-linking agents give impact
resistance to the impact reinforcement due to the formation of the
rubber structure on the impact reinforcement. The cross-linking
agent also provides a latex stability during the polymerization
reaction, and it enables the core to maintain a spherical form
during the processing steps.
The shell polymerization is generally performed by
graft-polymerizing alkyl methacrylate monomer, which is highly
compatible with polyvinyl chloride resin, on the core. To increase
a dispersibility of the impact-reinforcement, the shell may contain
small amount of an acrylonitrile monomer.
Two preparation methods of the acryl-based impact reinforcement,
which is prepared by emulsion polymerization, are disclosed. U.S.
Pat. No. 5,612,413 discloses a method, in which the impact
reinforcement is prepared by multi-step-emulsion polymerization
that includes polymerization of a seed having small particles,
polymerization of monomers in two or four steps to grow the seed,
and polymerization of monomers used for a shell therein in order to
form a core-shell structure wherein the core is enclosed within the
shell. European Patent No. 0,522,605A discloses a method, in which
an impact reinforcement is prepared by a micro-agglomeration method
comprising polymerizing a latex having a core-shell structure with
a particle size of 100 nm or less, agglomerating the particles to
prepare a latex with a desired particle size, and forming a
capsulated shell on the agglomerated particles.
However, there is a need to develop an impact reinforcement which
have an enhanced impact resistance to be used in place of the
impact reinforcement prepared by the conventional method.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an acryl-based
impact-reinforcement capable of enhancing an impact resistance.
It is another object to provide a preparation method of an
acryl-based impact-reinforcement for a polyvinyl chloride resin
capable of maximizing an impact strength by controlling the content
and size of rubber particles, the distance between the rubber
particles, and the swelling index of the rubber particles.
In order to achieve these objects, the present invention provides a
preparation method of an acryl-based impact-reinforcement
comprising blending a) 50 to 90 parts by weight of latex having
large particles with a particle size of 200 to 500 nm and a
core-shell structure; and b) 10 to 50 parts by weight of latex
having small particles with a particle size of 60 to 140 nm and a
core-shell structure.
In addition, the present invention further provides a polyvinyl
chloride resin compound prepared by using the invented impact
reinforcement.
DETAILED DESCRIPTION OF THE INVENTION
In the following detailed description, only the preferred
embodiment of the invention has been shown and described, simply by
way of illustration of the best mode contemplated by the inventors
of carrying out the invention. As will be realized, the invention
is capable of modification in various obvious respects, all without
departing from the invention. Accordingly, the drawings and
description are to be regarded as illustrative in nature, and not
restrictive.
An acryl-based impact-reinforcement of the present invention is
prepared by controlling the rubber particle content, the rubber
particle size, the distance between rubber particles, and the
swelling index of the rubber particles, all of which are critical
factors in determining impact strength of polyvinyl chloride resin.
In addition, the acryl-based impact-reinforcement is prepared by
polymerizing latex having large particles and latex having small
particles respectively, and blending the two latexes.
The effect of the rubber particle size on impact resistance will be
described. To prepare an impact reinforcement having impact
resistance in a matrix, it is necessary that a distance between
particles is maintained below a characteristic distance and that
particle size is maximized. Therefore, when the particle size of an
impact reinforcement is small (below 100 nm), the impact resistance
of the impact reinforcement decreases because the particle size is
small, although the inter-particle distance is below the
characteristic distance, and when the particle size of an impact
reinforcement is large (greater than 300 nm), the impact resistance
of the impact reinforcement decreases because the distance between
particles is above the characteristic distance.
Therefore, the acryl-based impact reinforcement of the present
invention is prepared by blending a latex having large particles to
enhance impact resistance with a latex having small particles to
decrease the distance between particles below the characteristic
distance.
The swelling index is a coefficient of swelling degree of a solvent
in gel, and an index of free volume of a polymer. As the
cross-linking density of rubber is increased, the swelling index
decreases, and as the cross-linking density of rubber is decreased,
the swelling index increases. The cross-linking density may be
controlled by amount of the cross-linking agent used in preparing
rubber, and as the amount of the cross-linking agent is decreased
to increase the swelling index, a greater impact resistance is
realized. However, when the amount of the cross-linking agent is
too small, it is difficult to control the swelling index since the
latex stability decreases during the polymerization reaction. In
the present invention, latex having large and small particles with
a swelling index of 2.0 to 12.0 is preferably used.
The acryl-based impact reinforcement is prepared by polymerizing a
seed, adding monomers used for the core thereto twice to four times
to grow the core rubber particle, adding monomers used for the
shell thereto enclosing the core within the shell. In order to
prepare a latex having large particles with a particle size of 200
to 500 nm and a latex having small particles with a particle size
of 60 to 140 nm, the same preparation method but the amount of
emulsifying agent was used and mixed the latexes having large
particles and small particles in a weight ratio of 5 to 9:1 to 5,
and coagulated.
It is preferable that a) latex having large particles and b) latex
having small particles respectively comprises a core having i) 97.0
to 99.9 parts by weight of alkyl acrylate with its alkyl group of
C.sub.2 to C.sub.8; and ii) 0.1 to 3.0 parts by weight of
cross-linking agent.
i) The alkyl acrylate preferably includes a monomer selected from
the group consisting of methyl acrylate, ethyl acrylate, propyl
acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, octyl
acrylate, and 2-ethylhexyl acrylate; and a homopolymer or a
copolymer thereof, and more preferably the alkyl acrylate includes
butyl acrylate, 2-ethylhexyl acrylate, or a mixture thereof.
ii) The cross-linking agent preferably includes at least one
monomer selected from the group consisting of 1,3-butanediol
diacrylate, 1,3-butanediol dimethacrylate, 1,4-butandiol
diacrylate, 1,4-butanediol dimethacrylate, allyl acrylate, allyl
methacrylate, trimethylol propane triacrylate, tetraethylene glycol
diacrylate, tetraethylene glycol dimethacrylate, and divinyl
benzene; and a homopolymer or a copolymer thereof. More preferably,
the cross-linking agent includes 1,3-butanediol diacrylate,
1,3-butanediol dimethacrylate, allyl acrylate, allyl methacrylate,
or a mixture thereof. The content of the cross-linking agent ranges
from 0.1 to 5.0 parts by weight based on the weight of the monomer
of the present invention. When the content of the cross-linking
agent is below 0.1 parts by weight based on the parts by weight of
the whole polymer, the spherical particles are easy to deform
during processing, and when the content of the cross-linking agent
is over 5.0 parts by weight based on the parts by weight of the
whole polymer, the core of the impact-reinforcement exhibits
brittle characteristics such that the impact-reinforcing capability
deteriorates.
a) The latex having large particles and b) the latex having small
particles respectively comprised of a shell having i) 80 to 100
parts by weight of the alkyl methacrylate with a carbon number of 1
to 4, they further comprised of ii) ethyl acrylate, methyl
acrylate, and butyl acrylate (a content of which is below 10 parts
by weight) in order to control a glass transition temperature of
the shell, and they may be comprised of iii) nitrites such as
acrylonitrile and methacrylonitrile (a content of which is below 10
parts by weight) in order to enhance a miscibility of the shell
with matrix.
In addition, the latex having large particles and the latex having
small particles comprise rubber monomer having 70 to 95 wt % of its
content based on that of the total monomer. When the rubber content
of the impact reinforcement is below 70 wt %, the
impact-reinforcement characteristics may deteriorate since the
impact-reinforcement has a small amount of rubber, and when the
content of the monomer rubber is over 95 wt %, the impact
resistance characteristics may deteriorate since the amount of the
shell is insufficient to encapsulate the core, and it is difficult
for the rubber to well dispersed in matrix.
The acryl-based impact-reinforcement of the present invention is
prepared by blending the latex having large particles and the latex
having small particles. During blending, the latex having large
particles is added to the latex having small particles. The blended
latex is coagulated with an electrolyte preferably such as calcium
chloride, after which filtering is performed to obtain the
impact-reinforcement.
A compound composition for polyvinyl chloride resin having good
impact-reinforcement comprises a) 80 to 99 parts by weight of
polyvinyl chloride resin; and b) 1 to 20 parts by weight of the
acryl-based impact-reinforcement.
Hereinafter, the preparation method of the acryl-based
impact-reinforcement will be described in detail. The preparation
method comprises main steps as follows:
1) Preparation of Latex Having Large Particles
The preparation method of the latex having large particles
comprises,
i) first polymerization of seed by cross-linking a mixture
comprising 97.0 to 99.9 parts by weight of alkyl acrylate with
carbon number of 2 to 8; 0.1 to 3.0 parts by weight of
cross-linking agent; 0.01 to 3.0 parts by weight of an initiator;
0.1 to 10.0 parts by weight of an emulsifying agent; and 1000.0
parts by weight of ion-exchange water at a temperature of 60 to
80.degree. C.;
ii) second polymerization of core rubber by emulsifying a mixture
comprising 97.0 to 99.9 parts by weight of alkyl acrylate with
carbon number of 2 to 8; 0.1 to 3.0 parts by weight of
cross-linking agent; 0.1 to 4.0 parts by weight of an emulsifying
agent; and 80 parts by weight of ion-exchange water, and adding the
emulsified mixture to the seed continuously while adding 0.01 to
3.0 parts by weight of an initiator thereto, and polymerizing these
elements together;
iii) third polymerization of core rubber by emulsifying a mixture
comprising 97.0 to 99.9 parts by weight of alkyl acrylate with
carbon number of 2 to 8; 0.1 to 3.0 parts by weight of
cross-linking agent; 0.1 to 4.0 parts by weight of an emulsifying
agent; and 80 parts by weight of ion-exchange water, and adding the
emulsified mixture to the second polymer continuously while adding
0.01 to 3.0 parts by weight of an initiator thereto, and
polymerizing these elements together; and
iv) fourth polymerization of a shell by emulsifying a mixture
comprising 80 to 100 parts by weight of alkyl methacrylate with
carbon number of 1 to 4; 10 parts by weight or less of alkyl
acrylate selected from the group consisting of ethyl acrylate,
methyl acrylate, and butyl acrylate; 10 parts by weight or less of
nitrile selected from the group consisting of acrylonitrile and
methacrylonitrile; 0.1 to 4.0 parts by weight of an emulsifying
agent; and 150 parts by weight of ion-exchange water, and adding
the emulsified mixture to the core continuously while adding 0.01
to 3.0 parts by weight of an initiator thereto, and polymerizing
these elements together in order to form the shell.
2) Preparation of Latex Having Small Particles
The preparation procedure of latex having small particles is the
same as that of latex having large particles. That is, the
preparation of latex having small particles comprises,
i) first polymerization of seed by cross-linking a mixture
comprising 97.0 to 99.9 parts by weight of alkyl acrylate with
carbon number of 2 to 8; 0.1 to 3.0 parts by weight of
cross-linking agent; 0.01 to 3.0 parts by weight of an initiator;
20 to 80 parts by weight of an emulsifying agent; and 1000.0 parts
by weight of ion-exchange water at a temperature of 60 to
80.degree. C.;
ii) second polymerization of core rubber by emulsifying a mixture
comprising 97.0 to 99.9 parts by weight of alkyl acrylate with
carbon number of 2 to 8; 0.1 to 3.0 parts by weight of
cross-linking agent; 0.1 to 4.0 parts by weight of an emulsifying
agent; and 80 parts by weight of ion-exchange water, and adding the
emulsified mixture to the seed continuously while adding 0.01 to
3.0 parts by weight of an initiator thereto, and polymerizing these
elements together;
iii) third polymerization of core rubber by emulsifying a mixture
comprising 97.0 to 99.9 parts by weight of alkyl acrylate with
carbon number of 2 to 8; 0.1 to 3.0 parts by weight of
cross-linking agent; 0.1 to 4.0 parts by weight of an emulsifying
agent; and 80 parts by weight of ion-exchange water, and adding the
emulsified mixture to the second polymer continuously while adding
0.01 to 3.0 parts by weight of an initiator thereto, and
polymerizing these elements together; and
iv) fourth polymerization of a shell by emulsifying a mixture
comprising 80 to 100 parts by weight of alkyl methacrylate with
carbon number of 1 to 4; 10 parts by weight or less of alkyl
acrylate selected from the group consisting of ethyl acrylate,
methyl acrylate, and butyl acrylate; 10 parts by weight or less of
nitrile selected from the group consisting of acrylonitrile and
methacrylonitrile; 0.1 to 4.0 parts by weight of an emulsifying
agent; and 150 part by weight of ion-exchange water, and adding the
emulsified mixture to the core continuously while adding 0.01 to
3.0 parts by weight of an initiator thereto, and polymerizing these
elements together in order to form the shell.
Any chemical that is capable of initiating polymerization reaction
can be used for the initiator in the preparation of the latex
having large particles or small particles, and exemplary initiators
include ammonium persulfate, potassium persulfate,
azobisbutyronitrile, benzoyl peroxide, butyl hydroperoxide, and
cumene hydroperoxide.
Ionic emulsifier or non-ionic emulsifier may be used as an
emulsifying agent applied in the preparation of the latex having
large particles or small particles: the ionic emulsifier includes
unsaturated fatty acid potassium salt, oleic acid potassium salt,
sodium lauryl sulfate (SLS), and sodium dodecyl benzene sulfate
(SDBS).
3) Preparation of an Acryl-based Impact-reinforcement
The latex having large particles and the latex having small
particles are blended at a ratio of 5 to 9:1 to 5, and ion-exchange
water is added thereto in order to lower the solid content of the
mixture to 10 wt %. 10 wt % of a calcium chloride solution is added
to the mixture in order to coagulate the polymer particles. The
temperature of the coagulated slurry is elevated to 90.degree. C.
and the slurry is aged and cooled. The cooled slurry is cleaned
with ion-exchange water, and filtered to obtain the acryl-based
impact-reinforcement.
The following Examples illustrate the present invention in further
detail. However, it is to understand that the present invention is
not limited by these Examples.
EXAMPLE 1
1) First Polymerization
461.3 g of ion-exchange water was added into a reactor, and the
temperature of the reactor was elevated to 75.degree. C. When the
temperature of the ion-exchange water in reactor reached 75.degree.
C., 49.3 g of butyl acrylate, 0.25 g of allyl methacrylate, 0.5 g
of 1,3-butandiol dimethacrylate, and 31.2 g of stearic acid
potassium salt (8 wt % solution) were added to the reactor. While
maintaining the reactor temperature at 75.degree. C., 0.42 g of
potassium persulfate dissolved in 10 g of the ion-exchange water
was added in order to initiate the polymerization reaction and
prepare the seed. The particle size of the prepared latex was
measured by laser light scattering (NICOMP), and it was 90 nm.
2) Second Reaction
366.7 g of ion-exchange water, 541.8 g of butyl acrylate, 2.75 g of
allyl methacrylate, and 5.5 g of 1,3-butandiol dimethacrylate, 68.8
g of steric acid potassium salt (8 wt % solution) were mixed
together in order to prepare an emulsified mixture. Keeping the
emulsified mixture continuously added into the seed latex at a
constant rate for 3 hours, 0.5 g of the potassium persulfate
dissolved in 10 g of ion-exchange water was further added therein
at a constant rate for 3 hours to procede core polymerization
reaction.
3) Third Reaction
121.2 g of ion-exchange water, 197.0 g of butyl acrylate, 1.0 g of
allyl methacrylate, 2.0 g of 1,3-butandiol dimethacrylate, and 31.3
g of stearic acid potassium salt (8 wt % solution) were mixed
together in order to emulsify a mixture thereof. The emulsified
mixture was added to the latex prepared by the second reaction
continuously for 1 hour at a constant flow rate. Simultaneously,
0.37 g of potassium persulfate dissolved in 10 g of ion-exchange
water was added thereto continuously for 1 hour. The reaction
mixture was aged for 1 hour while maintaining a reactor temperature
at 75.degree. C.
4) Fourth Reaction
To form a shell on the core of the third reaction, 267.0 g of
ion-exchange water, 182.6 g of methyl methacrylate, 10.0 g of ethyl
acrylate, 7.4 g of acrylonitrile, 25.0 g of stearic acid potassium
salt (8 wt % solution) were emulsified. The emulsion and 0.5 g of
potassium persulfate dissolved in 10 g of ion-exchange water were
added to the mixture of the third reaction continuously for 1.5
hours. The reaction mixture was further aged for 1 hour while
maintaining a reactor temperature of 75.degree. C., resulting in a
final latex. The particle size of the final latex was 250 nm.
EXAMPLE 2
The amount of 1,3-butandiol dimethacrylate added in the first to
third reactions of Example 1 was decreased by 1/2 in order to
increase the swelling index of the impact reinforcement. Except the
aforementioned, the latex was prepared by the same method as in
Example 1.
EXAMPLE 3
The 1,3-butandiol dimethacrylate added in the first to third
reactions of Example 1 was not used in order to further increase
the swelling index of the impact reinforcement. Except the
aforementioned, the latex was prepared by the same method as in
Example 1.
EXAMPLES 4 to 12
Latex having particle size of 350 nm, 80 nm, and 120 nm were
respectively prepared by controlling the amount of stearic acid
potassium salt added in the first reaction of Example 1. In
addition, the amount of 1,3-butandiol dimethacrylate was decreased
as the same manner in Example 2 and 3 in order to change the
swelling index of the impact reinforcement. Except the
aforementioned, the latex was prepared by the same method as in
Example 1. The amounts of stearic acid potassium salt and
1,3-butandiol dimethacrylate in the first step to third step, and
the final particle sizes of each latex according to Examples 4 to
12 are shown in Table 1.
TABLE-US-00001 TABLE 1 Amount of stearic Amount of 1,3-butandiol
acid dimethacrylate (g) potassium 1.sup.st 2.sup.nd 3.sup.rd
Particle size Example salt (g) reaction reaction reaction of latex
(nm) 4 21.3 0.5 5.5 2.0 350 5 21.3 0.25 2.75 1.0 350 6 21.3 0 0 0
350 7 375 0.5 5.5 2.0 80 8 375 0.25 2.75 1.0 80 9 375 0 0 0 80 10
112 0.5 5.5 2.0 120 11 112 0.25 2.75 1.0 120 12 112 0 0 0 120
EXAMPLE 13
In order to compare the impact strength of each Example, a standard
latex having particle size of 200 nm was prepared by controlling
the amount of stearic acid potassium salt (8 wt % solution) added
in the first reaction of Example 1 to 66.0 g and the 1,3-butandiol
dimethacrylate used in the first to third reactions was not added,
as in Example 3. Except the aforementioned, the latex was prepared
by the same method as in Example
EXPERIMENTAL EXAMPLE
Measurement of a Swelling Index of Latex
Polymerization results and swelling indexes of the latex according
to Examples 1 to 13 are shown in Table 2. The swelling index of the
latex was measured after coagulating the latex.
Ion-exchange water was added to the latex of Examples 1 to 13 in
order to decrease the solid content of the latex to 10 wt %, and 4
parts by weight of a 10 wt % calcium chloride solution was added
once thereto in order to coagulate the latex. The temperature of
each coagulated slurry was elevated to 90.degree. C. to age for 10
minutes, after which the slurry was cooled. The coagulated
particles were cleaned with ion-exchange water two or three times
in order to remove by-products from the latex, then it was filtered
to obtain the impact reinforcement. The coagulated impact
reinforcement was dried by using a fluidized bed dryer (FBD) at
85.degree. C. for 2 hours to obtain the impact reinforcement
powder.
4.0 g of the impact reinforcement powder were swelled in 130.0 g of
acetone for 50 hours to measure the swelling index of the impact
reinforcement. The swelled mixture was then centrifuged at
0.degree. C. and 1600 rpm for 2 hours to obtain the swelled gel,
and the mass of the swelled gel (A) was measured. In addition,
after evaporating the acetone, the mass of the pure gel with the
acetone removed (B) was measured, and the swelling index (=A/B) was
calculated.
Evaluation of Impact Reinforcement Properties
100 parts by weight of polyvinyl chloride resin (PVC, a product by
LG Chem., LS-100, degree of polymerization=1000), 4.0 parts by
weight of DLP, 0.9 parts by weight of calcium stearate (Ca-St),
1.36 parts by weight of polyethylene wax (PE wax), 1.0 parts by
weight of a processing aid (a product by LG Chem., PA-821), 5.0
parts by weight of CaCO.sub.3, and 4.0 parts by weight of TiO.sub.2
were added into a mixer at room temperature and mixed at 1000 rpm
while elevating the temperature to 115.degree. C. When the
temperature reached 115.degree. C., the mixing rate was slowed down
to 400 rpm and the mixture was cooled to 40.degree. C. to obtain a
master batch.
7 parts by weight of the impact reinforcement of the Examples were
respectively added to the master batch, and the resulting material
was processed by using a 2-roll-mill at 190.degree. C. for 7
minutes to shape the material into a sheet with a thickness of 0.6
mm. The sheet was cut to a size of 150 mm by 200 mm, and molded in
a mold of 3 mm by 170 mm by 220 mm. The molded sheet with a
thickness of 3 mm was prepared by preheating a hot press at
195.degree. C. for 8 minutes (0.5 kg), pressing the sheet with the
hot press for 4 minutes (10 kg), cooling the sheet down for 3
minutes (10 kg).
The obtained sheet was cut delicately according to the ASTM D-256
standard to prepare specimen for the impact test, and its Izod
impact strength was measured. The test results of Examples 1 to 13
are represented in Table 2.
TABLE-US-00002 TABLE 2 Particle Cross-linking Swelling Izod impact
test Examples size (mm) agent (wt %) index (kg cm/cm) Example 1 250
1.5 3.1 30.3 Example 2 250 1.0 5.3 38.5 Example 3 250 0.5 8.7 47.3
Example 4 350 1.5 3.1 35.7 Example 5 350 1.0 5.4 38.4 Example 6 350
0.5 8.8 42.5 Example 7 80 1.5 3.0 24.7 Example 8 80 1.0 5.2 26.9
Example 9 80 0.5 8.6 29.4 Example 10 120 1.5 3.0 28.1 Example 11
120 1.0 5.1 30.1 Example 12 120 0.5 8.7 33.7 Example 13 200 0.5 8.7
50.9
EXAMPLES 14 to 17
Each of two latexes having large particle with particle size of 250
nm and the swelling index of 8.7 according to Example 3 and with
particle size of 350 nm and the swelling index of 8.8 according to
Example 6 was blended a weight ratio of 10:0, 7:3, 5:5, 3:7, and
0:10 with each of two latexes having small particle with particle
size of 80 nm and the swelling index of 8.6 according to Example 9
and with particle size of 120 nm and the swelling index of 8.7
according to Example 12. Each blended latex was coagulated to
prepare impact reinforcement powder and specimen was prepared with
the same method of Evaluation of impact reinforcement properties.
The test results of each blended impact reinforcement are shown in
Table 3.
TABLE-US-00003 TABLE 3 Latex having Impact strength (kg cm/cm) with
large particles + Latex mixing ratio of latex having large having
particles:latex having small particles small particles 10:0 9:1 8:2
7:3 6:4 5:5 3:7 0:10 Example Example 3 + 47.3 54.3 55.1 53.7 51.5
48.7 38.2 29.4 14 Example 9 Example Example 3 + 47.3 53.0 54.3 55.4
53.5 50.1 42.0 33.7 15 Example 12 Example Example 6 + 42.5 50.9
55.8 54.3 52.5 50.6 42.9 29.4 16 Example 9 Example Example 6 + 42.5
49.2 52.5 55.6 55.5 51.7 40.3 33.7 17 Example 12
As shown in Table 3, when the blending ratio of latexes having
large particles and small particles was in the range of 5 to 9:1 to
5, the impact strength was high, and the impact reinforcement of
the present invention showed enhanced impact-resistance compared to
the standard impact reinforcement of particle size of 200 nm
according to Example 13 (cf. 10 Table 2).
EXAMPLES 18 to 21
Each of two latexes having large particle with particle size of 350
nm and the swelling index of 3.1 according to Example 4 and with
particle size of 350 nm and the swelling index of 8.8 according to
Example 6 was blended at a weight ratio of 10:0, 7:3, 5:5, 3:7, and
0:10 with each of two latexes having small particles with particle
size of 80 nm and the swelling index of 3.0 according to Example 7
and with particle size of 80 nm and the swelling index of 8.6
according to Example 9, to prepare impact reinforcement having
different particle sizes and swelling indexes. The impact strength
of the each impact reinforcement was measured and represented in
Table 4.
TABLE-US-00004 TABLE 4 Impact strength (kg cm/cm) Latex having
large with mixing ratio of latex particles + Latex having large
particles:latex having small having small particles particles 10:0
7:3 5:5 3:7 0:10 Example Example 4 + 35.7 43.3 40.1 34.8 24.7 18
Example 7 Example Example 4 + 35.7 48.2 43.4 36.9 29.4 19 Example 9
Example Example 6 + 42.5 53.6 48.5 38.4 24.7 20 Example 7 Example
Example 6 + 42.5 54.3 50.6 41.3 29.4 21 Example 9
As shown in Table 4, the latex having large particles with
different swelling index is mixed with the latex having small
particles with different swelling index to prepare an impact
reinforcement, in which the impact resistance of the impact
reinforcement increases when the large particle mass ratio is in
the range of 50 to 90% in the case where its large particle size
ranges from 250 to 400 nm and its small particle size ranges from
80 to 120 nm. In addition, comparing the impact resistance of
Example 18 to that of Example 19, the impact strength is higher in
Example 18 where the swelling index of the latex ranges from 8 to
9.
A preparation method of the present invention relates to a method
of preparing an acryl-based impact reinforcement having an enhanced
impact strength resulting from controlling the rubber content, the
size of the rubber particles, the distance between the rubber
particles, and the swelling index of the rubber particles.
While the present invention has been described in detail with
reference to the preferred embodiments, those skilled in the art
will appreciate that various modifications and substitutions can be
made thereto without departing from the spirit and scope of the
present invention as set forth in the appended claims.
* * * * *